The conventional method of intramedullary nailing of a fractured or broken femur, as shown in FIG. 1A, requires first placing the patient 100 on the fracture table 110 for the surgical treatment e.g., intramedullary nailing of a left femur. The patient is shown to be in a supine position, that is, lying on his/her back. The feet are placed in a traction device 120 which holds the femur stretched out to length. In the majority of cases, this will be sufficient to allow the surgical procedure to proceed. FIG. 1B shows a frontal projection of the patient 100 in the supine position.
The position of the broken fragments is monitored by an x-ray machine called a “fluoroscopy machine” (not shown) which provides real-time x-ray images to the surgeon. It will be recognized that some surgeons would prefer that the patient be placed on the side with the injured extremity extending upwards. FIG. 1C shows a posterior projection of a patient 100 placed in the lateral position, with the patient 100 on his/her side. FIG. 1D shows a frontal projection of the patient 100 on the fracture table 110 in the lateral position, with the fractured side upwards.
Referring to FIGS. 2A–2F, after the location of the incision in the applicable thigh and femur is prepared by cleansing and sterilizing, an incision 200 is made over the proximal end 212 of the femur 210 in the area that will be referred to as the “greater trochanter” 214. FIG. 2A depicts an incision 200, with the normal dissection performed on the area of the trochanter 214 and the neck 216 of the femur 210, which is the broken bone in the present example. Proper retraction is made with the tracking table 110 and the startable area is identified. This is just medial to the greater trochanter 214 described above.
A starter hole 202 can be made using either of two procedures. An awl 220, as shown in FIG. 2B, or a guide wire with a sharp end (not shown) is used to make the starter hole. FIGS. 2B′ and 2B″ depict different views of the awl 220 as it makes the starter hole.
Once the starter hole is made, reaming using reamer 230 is begun. Reaming is usually performed over a guide wire. In some cases, if the traction described earlier does not place the broken fragments in the proper alignment and reduction, a procedure can be performed, after partial reaming from the proximal end 212, across the fracture 219, to the distal end 218 of the main proximal fragment, to insert a short internal fracture alignment device (not shown) or short intermedular rod (not shown) to improve the alignment reduction. The reaming at different stages is shown in FIGS. 2C and 2D.
Once the fracture is sufficiently reduced and aligned, with proper length restoration attained to the satisfaction of the surgeon, a guide wire 240 with a ball tip 242 is inserted with a hammer (not shown). The guide wire 240 is pushed down through the intermedular area to the distal end 218 of the femur 210. That is, the guide wire 240 is pushed into the distal fragment. Usually the guide wire 240 will stop at a desired area, such as the old epiphyseal line or just proximal to the kneecap in the present example. The positions of the guide wire 240 are monitored using the fluoroscopy machine as described above. FIG. 2E depicts the termination of the ball tip guide wire 240. It will be noted that the guide wire 240 has calibrations 244 to show how deep the wire has been inserted. This enables the surgeon to choose the appropriate length of the nail. Alternatively, as shown in FIG. 2E, the determination of nail length can be made by using a metal ruler 246 strapped to the skin. With the ruler 246, the necessary depth and the necessary length of the nail are determined using the fluoroscopy machine.
FIG. 2F depicts the reaming process over an already implanted ball tipped guide wire 240. The reaming with the reamer 230 proceeds up to the desired diameter of the nail. For each individual patient there are limitations on the reamed diameter due to the constraints of the cortical surfaces. The determination of precisely how much reaming to do is made by the surgeon on a case-by-case basis.
Referring now to the images in FIGS. 3A and 3B, after the reaming of the intermedullary cavity of both fragments, i.e. the bone on both sides of the fracture 219, the proximal fragment 212 which broke and the distal fragment 218 of the femur 210 remain aligned and traversed by a ball tipped guide wire 240. A plastic sleeve (not shown) is inserted into the reamed cavity over the ball tipped guide wire 240. This allows removal of the guide wire 240 while still maintaining the alignment and reduction attained in the previous steps. Another guide wire 300 is inserted through the plastic sleeve. This latter guide wire 300 does not have a ball tip at the end, and is therefore easily removable after insertion of a nail into the reamed cavity.
FIG. 3A depicts the initial insertion of the nail 310 into the reamed cavity. FIG. 3B shows the nail 310 being inserted with an attached handle 322 and jig 320 to allow hammering of the nail 310 to its proper depth with a hammer or slaphammer (as shown). Attached to the jig 320 in FIG. 3B is an angle guide 324. After the nail 310 is seated, the angle guide 324 is used to prepare the nail for a locking screw or screws.
Referring now to FIGS. 4A and 4B, the jig 320 is shown in place, with the hammer or slaphammer removed. As shown in FIG. 4A, a drill 400 is aligned by the jig 320 to be at a predetermined angle in order to ensure that the drill bit 402 will be directed through the predrilled holes in the nail 310 and will exit at the lesser trochanter 213, which is the smaller prominence on the opposite side of the bone from the greater trochanter 214. As shown in FIG. 4B, after drilling, a depth gauge 410 is used to select the proper length of the locking screw. At this point it should be noted that in some fractures of the femur 210, the surgeon may decide that the locking screw should go essentially from the greater trochanter area 214 through the predrilled hole in the nail 310, and be fixed firmly into the lesser trochanter 213. On the other hand, the surgeon may decide that, because of the fracture, a different type jig (not shown) will be used to allow insertion of a screw or screws into the femoral neck 216 and head of the femur 210. The choice is made by the surgeon on a case-by-case basis.
It should also be noted that, in many cases, it is considered necessary to secure the reduction obtained by the traction described above, both proximal and distal locking screws are necessary. Using a jig 500, such as that shown in FIGS. 5A and 5A′, to secure distal locking of the nail 310, which typically has two holes in its distal portion, has not been very successful in practice. Variations in position of a millimeter or more can make it very difficult to insert distal locking screws.
This is because the surgeon must place the screws through an incision similar to the proximal incision described above, up through cortical bone, and into the predrilled holes in the metal intermedullary nail 310. A misalignment of a millimeter or so will make it impossible to advance the screws through the near cortex and both cortices of the nail 310, and to be secured in a far cortex. Therefore, in practice, distal locking jigs 500 have generally been abandoned because of the great difficulty experienced in successfully in placing distal locking screws using a jig technique.
Instead, the freehand technique is commonly used by surgeons today. The freehand technique requires a sharp tipped awl 500 or a sharp tipped guide wire (not shown). A fluoroscopy machine 520 is also used in this technique. Using this technique, the surgeon must place his/her hand in the field of radiation emitted by the fluoroscopy, i.e. x-ray, machine. In accordance with this technique, the fluoroscopy machine 520 is moved so that the distal holes 312 in the nail 310 perfect circles in the fluoroscopy image, as shown in FIG. 5C. Once these perfect circles are obtained, the distal end of the awl 510 or the sharp tipped rigid guide wire is aligned perfectly with this round hole. This must be done twice, since it is generally recommended that at least two distal locking screws of appropriate size be placed to fix the distal portion of the nail 310 to the femur 210. This is very difficult to do and exposes the surgeon, who may be required to perform the freehand technique a number of times each month or year, to dangerous levels of radiation.
FIG. 5B depicts the maneuvering required in the freehand technique to try to place the tip of the awl 510 in the perfectly circular holes. Once the surgeon considers the awl 510 to be properly positioned, a starting hole is made by the awl to start the hole in the near cortex 215 of the femur 210. After this is completed, and the image of the hole remains a perfect circle, i.e. the hole 312 stays where it is supposed to be according to the fluoroscopy machine 520, a power drill is used to make the hole through the near cortex, so as to be perfectly aligned with the hole 312 in the nail 310. The drilled hole extends from the near side of the nail 310 to the far side of the nail, and then finally into the far side of the cortex. If this is successful, a depth gauge is used to determine the proper screw length and then the screw is placed, as the drill was, across the near cortex of the femur 210, the near cortex of the nail, the far cortex of the nail 310 and the far cortex of the femur.
Needless to say, the fluoroscopy machine 520 has to stay positioned throughout the procedure, because even after drilling it can be difficult to find the weight bearing drilled nail hole 312. As noted above, this procedure must be repeated to allow placement of two or more screws. The femur 210 will take four to eight months to heal, before weight bearing is allowed. In the vast majority of the cases, if only one distal screw is used it will break, making the bone more susceptible to infection and making removal of the screw fragments almost impossible.
FIGS. 5C and 5C′ demonstrate the use of the fluoroscopy machine 520 to show the difference in the profile of the predrilled holes 312 in the distal nail 310. A non-circular hole is shown in FIG. 5C′ and a perfectly circular hole is shown in FIG. 5C.